In general, since a secondary battery may be charged and discharged unlike a primary battery, the secondary battery has been applied in various fields such as a digital camera, a mobile phone, a notebook, and a hybrid car, and research into the secondary battery has been actively conducted. As the secondary battery, there are a nickel-cadmium battery, a nickel-metal hydride battery, a nickel-hydrogen battery, and a lithium secondary battery. Further, among the above-mentioned secondary batteries, various researches into the lithium secondary battery having high energy density and discharge voltage have been conducted, and the lithium secondary battery has been commercialized and widely used.
In addition, the secondary battery is configured in a form of a battery module in which a plurality of battery cells are stacked due to a necessity for high power and high capacity. In this case, a temperature in the cell may be instantly increased due to generation of overcharge at the time of operation of the battery cell or generation of an internal short-circuit caused by a defect in a specific cell of the plurality of cells, or the like, such that gas is generated, thereby expanding a volume of the battery cell. In addition, it is difficult to assemble each of the battery cells due to dimensional tolerance at the time of manufacturing the battery cells. Therefore, a separate insulation pad is interposed between the battery cells, such that volume expansion and dimensional tolerance of the battery cell may be absorbed.
However, since the insulation pad interposed between the battery cells is heavy and expensive, in the case of the battery module or battery pack assembled by stacking a plurality of battery cells, an overall weight and cost may be further increased.
As the related art, “Battery systems, Battery Modules, and Method for Cooling Battery Module” has been disclosed in U.S. Patent Application Publication No. 20100279152.